Form personalization to update a given DFF of all order open lines when a specific DFF is modified i

Dear all,

In sales orders, we would like to have "dependant information" between a header DFF and a line DFF. I mean that when user updates the DFF at header level of an order, it would automatically change the "related" dff at line level with same value on all open lines of the order:

If :ORDER.ATTRIBUTE18 is updated, field :LINE.ATTRIBUTE11 is automatically updated with same value for all open lines of the order.

I read that it is not possible to manage this with defaulting rules (DFF not availalbe in defeulting rules) neither can we do it in the oe_dependencies_extn package as source and dependent attributes are not in same entity.